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Antiviral medicines to treat COVID-19 are still scarce. Porphyrins and porphyrin derivatives (PDs) usually present broad-spectrum antiviral activity with low risk of resistance development. In fact, some PDs are clinically approved to be used in anti-cancer photodynamic therapy and repurposing clinically approved PDs might be an alternative to treat COVID-19. Here, we characterize the ability of temoporfin, verteporfin, talaporfin and redaporfin to inactivate SARS-CoV-2 infectious particles. PDs light-dependent and –independent effect on SARS-CoV-2 infectivity were evaluated. PDs photoactivation successfully inactivated SARS-CoV-2 with very low concentrations and light dose. However, only temoporfin and verteporfin inactivated SARS-CoV-2 in the dark, being verteporfin the most effective. PDs treatment reduced viral load in infected Caco-2 cells, while not inducing cytotoxicity. Furthermore, light-independent treatment with temoporfin and verteporfin act on early stages of viral infection. Using lipid vehicles as membrane models, we characterized PDs interaction to the viral envelope. Verteporfin presented the lowest IC50 for viral inactivation and the highest partition coefficients (K p) towards lipid bilayers. Curiously, although temoporfin and redaporfin presented similar K p s , redaporfin did not present light-independent antiviral activity, and only temoporfin and verteporfin caused lipid membrane disorder. In fact, redaporfin is located closer to the bilayer surface, while temoporfin and verteporfin are located closer to the centre. Our results suggest that viral envelope affinity, with penetration and destabilization of the lipid bilayer, seems critical to mediate PDs antiviral activity. Altogether, these findings open new avenues for the off-label application of temoporfin and verteporfin in the systemic treatment of COVID-19. [Display omitted] • Photoactivation of clinically approved porphyrin derivatives inactivated SARS-CoV-2. • Temoporfin and verteporfin inactivated SARS-CoV-2 and ZIKV in the dark. • Porphyrin derivatives deep membrane penetration promotes membrane destabilization. • Virus inactivation by porphyrin derivatives depends on membrane destabilization. [ABSTRACT FROM AUTHOR]

The design of novel molecular structures with tunable photophysical properties is an important research field for many applications including optoelectronics, sensing and bioimaging. Porphyrin and rhodamine/rosamine derivatives are among the most studied and relevant chemosensors and imaging probes due to their attractive photophysical properties, such as high absorption coefficients and long emission wavelengths. In this work, we present the synthesis and the structural characterization of a new porphyrin–rosamine conjugate H 2 P3 and its related triarylmethane precursors H 2 P1 and H 2 P2. The photophysical properties of H 2 P1 , H 2 P2 and H 2 P3 , and their ability to chelate iron(III) and copper(II) ions, were evaluated by absorption and emission spectroscopy. The formation of copper(II) complexes was confirmed by electron paramagnetic resonance (EPR), which also allowed the detection of an intense and stable radical signal for the free-base H 2 P3. Further studies involving the addition of the 2,2,6,6-tetramethylpiperidine spin trap to derivatives H 2 P1 , H 2 P2 and H 2 P3 , showed that only H 2 P3 gives rise to an EPR detectable signal due to a strong generation of singlet oxygen. • Efficient access to a new porphyrin−rosamine conjugate and to related triarylmethane precursors. • The photophysical characterization shows that the low fluorescence emission of porphyrin–rosamine conjugate is due to the xanthene ring. • The coordination of the new compounds towards Fe(III) and Cu(II) can be related with the difference in the oxidation state of the two metals. • The EPR of the porphyrin−rosamine conjugate shows the presence of radical species. • The porphyrin–rosamine conjugate, in the presence of TEMP spin trap, leads to a EPR signal due to the formation of singlet oxygen. [ABSTRACT FROM AUTHOR]

Meso-tetrakis(1,2-dimethylpyrazolium-4-yl)porphyrin sulfonate (TDMPzP), a water-soluble porphyrin derivative, was synthesized and used as a colorimetric reagent for Cu 2+ detection on a microfluidic paper-based analytical device (µPAD) using distance-based quantification. TDMPzP showed a high selectivity for Cu 2+ detection in aqueous solutions. When Cu 2+ was added to the TDMPzP under acidic conditions, a color change from green to a pink was observed by the naked eye. Under optimized conditions, the application of this system to a distance-based μPAD exhibited good analytical response. The presence of common metal ions (Al 3+ , Fe 3+ , Mg 2+ , Co 2+ , Mn 2+ , Zn 2+ , Pb 2+ , Cd 2+ , Sn 2+ , and Ni 2+ ) did not interfere with Cu 2+ detection within reasonable tolerance ratios. The lowest concentration of copper that could be measured was 1 mg L −1 (1 ppm) which meets the requirements for drinking water contamination regulations from the US Environmental Protection Agency (EPA) and World Health Organization (WHO) guidelines for drinking water. Real drinking water samples were analyzed to confirm the practical application of this system and the results showed good agreement with ICP-MS data. This distance-based µPAD based on TDMPzP for Cu 2+ detection is convenient and effective for real-time drinking water analysis. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) relies on the generation of cytotoxic singlet oxygen (1O 2) from an otherwise nontoxic photosensitizer accumulated in tumor tissue to treat cancer. However, PDT of uveal melanoma, the most common adult intraocular cancer, using potent porphyrin derivatives as photosensitizers has shown limited therapeutic efficacy due to low bioavailability and 1O 2 yield. Here, considering the uveal melanoma microenvironment of endogenous melanin, which has a high absorption between 300 nm and 500 nm, we design a carbon dot-based photosensitizer that uses multiple different pathways to generate 1O 2. We conjugated gadolinium (Gd)-doped carbon dots (Gd@Cdots) with the porphyrin-derivatives chlorin e6 (Ce6) and verteporfin (Ver). The resulting nanoparticle (Gd@Cdots/Ce6/Ver) generates 1O 2 under UV irradiation mainly in cascade FRET from Gd@Cdots to Ce6 and then to Ver; the photoactivated Ver, in turn, transfers its energy to 3O 2 to generate 1O 2. In human uveal melanoma MUM-2B cells in vitro, Gd@Cdots/Ce6/Ver generated 7.1- and 2.4-fold higher production of hydroxyl radical (·OH) and superoxide anions (O 2 -·) following UV irradiation than Gd@Cdots, indicating greater induction of tumor cell apoptosis. In an orthotopic mouse model of uveal melanoma, PDT with Gd@Cdots/Ce6/Ver showed the same trend of superior potency in tumor growth inhibition. This photosensitizer design improves the PDT efficacy of uveal melanoma by enhancing the production of 1O 2 and should be of broad utility to other PDT. [Display omitted] • A cascade FRET photosensitizer for photodynamic therapy of ocular melanoma is developed. • The cascaded photosensitizer has highly coincident absorption light range with melanin which is highly expressed in ocular melanoma. • The cascaded FRET photosensitizer yield 1O 2 and ROS via multiple photoactivation pathways. • The cascaded photosensitizer shows superior potency in tumor growth inhibition and little side effect on normal tissues. [ABSTRACT FROM AUTHOR]

Because it is highly infiltrative, malignant glioma is a cancer with a poor prognosis despite multidisciplinary treatment strategies, such as aggressive surgery and chemoradiotherapy, necessitating new therapeutic approaches to control migration of tumor cells. In our study, we investigated the efficacy of sonodynamic therapy of glioma cells in vitro using porphyrin derivatives, including 5-aminolevulinic acid, protoporphyrin IX and talaporfin sodium, as sonosensitizers. These substances have been known to accumulate in glioma cells and are expected to have cytotoxic effects on sonication. Our study found that the cytotoxicity of sonication of glioma cells is enhanced by each sonosensitizer and that the efficacy of sonodynamic therapy may depend on the degree of intracellular accumulation of sonosensitizer. Also, the study suggests that induction of apoptosis is a major mechanism underlying cell death. Though further investigations are necessary, our preliminary result indicates a potential for sonodynamic therapy with sonosensitizers in glioma treatment. [ABSTRACT FROM AUTHOR]

In this work, in order to improve the low solubility and expand the applications of porphyrins in polysiloxanes, a series of designed siloxane-modified porphyrin derivatives was fabricated based on the Piers-Rubinsztajn reaction. The solubility of the porphyrin derivatives in polysiloxanes could be controlled by adjusting the siloxane chain length. Furthermore, the silicone-modified porphyrin derivatives were doped into a silicone elastomer prepolymer to obtain luminescent elastomers, which also showed good transparency and interfacial stability. In addition, the thermal stability and mechanical properties were well preserved compared with the original elastomer. Finally, based on the above-mentioned properties, an organosilicon elastomer doped with porphyrin showed good processability and plasticity, and could be fabricated into various complex three-dimensional models. The designed siloxane-modified porphyrin derivatives were fabricated using the Piers-Rubinsztajn reaction. Doping them into a silicone prepolymer produced homogeneous luminescent elastomers for the processing of 3D materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] SWV were recorded for MPtz x Ph4−xPorph (x =0, 1, 2, 4; M=Ni2+, Cu2+, Pd2+). [•] Ptz and Porph contribute distinctly to the overall redox response. [•] Ptz and M2+ exert opposite effects on the redox activity of the Porph ring. [•] Structure–redox activity correlation obeys Hammett’s free energy relationship. [•] The spectral activity of the investigated compounds is decided by the Porph moiety. [Copyright &y& Elsevier]

Abstract: The aim of this study was to examine and determine binding affinities of the peripheral benzodiazepine receptor (PBR) with diamino acid derivatives of protoporphyrin IX with general structure PP(AA)2 in a function of environmental pH changes. Fluorescence intensity was used as a measure of protein association constant. Decrease in protein fluorescence, after titration with increasing concentration of porphyrins, gave evidence of interactions between PBR and examined ligands. Experimental data were fitted to theoretical curves, assuming different models of interactions. All examined ligands were best fitted to weak binding model. Increase in environmental acidity resulted in changes in association constants. For all examined derivatives association constants were at least twice higher in pH 5.5 as compared to pH 7.4 and 6.5. [Copyright &y& Elsevier]

Abstract: Porphyrins are known to play a significant role in several biological systems. The research conducted for many years proved the versatility of applications involving porphyrin, often including the different areas of life [M. Gouterman, in: D. Dolphin (Ed.), The Porphyrins, vol. III, Academic Press, 1978, p. 1]. They can be used as active elements of biosensors, molecular switching devices and in non-linear optical materials, and in photodynamic cancer therapy as well. High quality optical materials with extremely good thermal and chemical stabilities can be produced by using a technique of silica sol–gel derived matrices [M. Rui Pereira, J.A. Ferreira, G. Hungrford, J. Photochem. Photobiol. 172 (2005) 7–17; J. Sokolnicki, R. Wiglusz, S. Radzki, A. Graczyk, J. Legendziewicz, Opt. Mater. 26 (2004) 199–206; R. Reisfeld, New materials for nonlinear optics. Optical and electronic phenomena in sol–gel glasses and modern applications, in: R. Reisfeld, C.K. Jorgensen (Eds.), Struct. Bond. 85 (1996) 99–147; B.G. Gregg, M.A. Fox, A.J. Bard, J. Am. Chem. Soc. 111 (1989) 3024; M. Ochsner, J. Photochem. Photobiol. 39 (1997) 1]. Recently, we have reported the photophysical behavior of the selected porphyrins contained within solution and entrapped in silica sol–gel derived matrices [J. Sokolnicki, R. Wiglusz, S. Radzki, A. Graczyk, J. Legendziewicz, Opt. Mater. 26 (2004) 199–206; R. Wiglusz, J. Legendziewicz, A. Graczyk, S. Radzki, P. Gawryszewska, J. Sokolnicki, J. Alloys Compd. 380 (2004) 396–404]. The present paper is devoted to photophysical characteristics of new – also chiral – porphyrins, and incorporated in silica sol–gel matrices; perspective chiral biosensors. In this paper, the synthesis and spectroscopic studies of porphyrin derivatives, at room and low temperatures in solutions and hybrid organic–inorganic materials obtained in different conditions by the sol–gel route are performed. An effect of different factors on emission efficiency is discussed. [Copyright &y& Elsevier]

Abstract: Conformations of two dodecameric porphyrin wheels adsorbed on a Cu(100) were probed by using scanning tunneling microscopy (STM). Whereas a wheel consisting of six meso–meso linked diporphyrins was detected as uniform ring structure, several different images with three discrete molecular heights were detected for a wheel consisting of six meso–meso, β-β,β-β triply-linked planar diporphyrins. These results indicate that the former has a conformation similar to that in a free space, while the latter has various conformations with respect to orientation of planar diporphyrin units toward the metal surface. Several discrete STM images of the latter have been interpreted in terms of possible eight conformations, which vary as to relative orientation of neighboring diporphyrin units. [Copyright &y& Elsevier]

Abstract: Electronic structures, one- and two-photon absorption (TPA) properties of zinc(II)-porphyrin compound (Z H ), meso–meso singly-linked zinc(II)-diporphyrin compound (Z2 H ) and zinc(II) meso,meso-coupled porphyrin dimer (Z2 H -G) via intermolecular hydrogen bonding interactions have been comparatively studied by using ZINDO–SOS method. The results show that formation of hydrogen bondings between carboxyl groups and cyclic urea reduces the dihedral angle between the adjacent porphyrin planes in Z2 H -G, leading to increased electronic interactions between the two porphyrin planes and increased couplings between electronic states. Electronic spectrum of Z H can be described with the four-orbital model, while the descriptions of the electronic spectra of Z2 H and Z2 H -G need eight frontier orbitals. Theoretical calculations reveal that TPA cross sections increase on going from Z H to Z2 H to Z2 H -G due to increase of the couplings between electronic states through transition dipole moments. [Copyright &y& Elsevier]

Twenty four aminoporphyrin derivatives have been tested in vitro for their antibacterial photoactivity against Escherichia coli and Staphylococcus aureus. Two of these compounds, bearing polyamine units, exhibited a significant activity especially against Gram-negative bacteria (E. coli). [Copyright &y& Elsevier]

The need for new, chemically and physically stable luminescent materials operating with UV excitations has stimulated research on luminescence properties of doped sol–gel material. In this work we present technology of production of silica gels doped with organic molecules, lanthanide compounds and organic/inorganic composites. Optical properties of these materials as functions of temperature, concentration and excitation wavelength are presented. Dynamics of the excited states is discussed based on the decay times and emission efficiencies data. Mechanisms of ligand-to-metal energy transfer as well as other processes affecting emission efficiency are considered. Silica sol–gels doped with di-aminoacid derivatives of porphyrins: PP(Ser)2(Arg)2, PP(Ala)2(Arg)2, PP(Met)2(Arg)2, where Met, Arg and Ser denote methionine, serine and arginine aminoacids, respectively, and H2TTMePP {tetrakis[4-(trimethylammonio)phenyl]-21H,23H-porphine} have been obtained and spectroscopically studied. The samples emit only from the lowest excited singlet state (S1). Intensity of this emission depends on the concentration of the active molecule and time of the exposition to the excitation beam. The sample containing PP(Ser)2 (Arg)2 co-doped with Tb(III) ions exhibits only 5D4 emission from the metal center. When co-doped with Pr(III) ions it displays only the S1 emission and it has been shown that the metal ions affect the S2 → S1 internal conversion. These materials can find applications as phosphors or sensors of UV irradiation. The efforts have been undertaken also to obtain chiral anisotropic materials. [Copyright &y& Elsevier]

Using density functional theory and ZINDO-SOS method, the two-photon absorption properties of a series of porphyrin derivatives have been theoretically investigated. The calculated results are in good agreement with the experimental observations. It is found that the central porphyrin moiety has the electron-donating ability, which is favor of the charge transfer from the center to the electron acceptor ends. As a consequence, the compound [5,15-bis[(4′-nitrophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II) presents the largest two-photon absorption cross-section—3279×10-50cm4 s/photon, which is more than 100 times as that for (porphinato)-zinc (II). This type of symmetrically substituted porphyrin derivatives will be a promising direction for further development of novel TPA dyes. [Copyright &y& Elsevier]

The ligand substitution reaction of K[Ru2(dhpta)(μ-O2CCH3)2] (H5dhpta=1,3-diamino-2-hydroxypropanetetraacetic acid) with zinc 5-(4-carboxylphenyl)-10,15,20-triphenylporphyrin (ZnTPP-p-COOH) afforded a diruthenium complex having porphyrin moieties, K[Ru2(dhpta)(μ-O2C-p-ZnTPP)2]. This product was characterized by UV–Vis and 1H NMR spectroscopy, and EXAFS analysis. [Copyright &y& Elsevier]

The photochemical and photoelectrochemical properties of two porphyrin derivatives with different numbers of carboxyl groups were investigated. The two porphyrin derivatives are 5-(4-carboxyphenyl)-10,15,20-tritolylporphyrin (H2TC1PP) and 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (H2TC4PP). The interaction between the porphyrin and TiO2 is determined by the UV–vis spectra. Differences in adsorption behavior of the two porphyrin derivatives on the TiO2 electrode surface were observed. The IR data suggest that both of the porphyrins adsorb by bridging or bidentate chelate coordination on the TiO2 surface. Comparing the luminescence spectra of the two porphyrins in solution and the solid state, no spectral difference was observed. However, we found that the variation in the number of carboxyl groups has an influence on the fluorescence spectra of the adsorbed TiO2 electrode. Furthermore, we measured and compared the incident photon-to-current conversion efficiency (IPCE) and the light-to-electrical conversion efficiency of the porphyrin-sensitized solar cell. These results revealed that the number of functional groups influenced the photoelectrochemical properties of the cell. [Copyright &y& Elsevier]

A series of porphyrin derivatives containing carboxylic-, sulfo- and hydro- groups, 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (TCPP), 5,10,15,20-tetrakis(4-sulfophenyl)porphyrin (TSPP) and 5,10,15,20-tetraphenyl-porphyrin (TPP), were examined as sensitizers for porous nanocrystalline TiO2. The difference in the adsorption behavior on the TiO2 electrode surface was discussed. The interaction between the porphyrins and the TiO2 surface was determined and compared using UV–Vis spectra and X-ray photoelectron spectroscopy (XPS). The luminescence spectra of the porphyrins in DMF solution and adsorbed onto TiO2 electrodes were measured. The ionization potentials of the porphyrins in the solid state and adsorbed onto TiO2 electrodes were determined by a new approach using an apparatus for measuring the emission yield under atmospheric conditions. The importance of the binding states between the dye and TiO2 surface was discussed by comparison of the energy conversion efficiency in a dye-sensitized solar cell. The results indicate that the binding state and the amount of adsorbed dye are important factors affecting the properties of the dye-sensitized solar cell. [Copyright &y& Elsevier]

Meso-(2-thienyl) porphyrin derivatives were synthesized. Excited state reverse saturable absorption was observed at 532 nm while two-photon absorption was observed at 800 nm. The nonlinear optical properties are increased by introducing the donator of thienyl group. Meso-(2-thienyl) porphyrin derivatives showed good nonlinear response at low energy. High third-order nonlinear optical susceptibility values (10−10 esu) of metal-free porphyrin derivatives were obtained. The mechanisms of third-order nonlinearity were proposed by the pump-probe experiment. With the observed fast electronic nonlinearities the studied molecules are potential candidates for use as optical limiters or optical switches. • Three new meso-(2-thienyl)porphyrin derivatives were synthesized. • These metal-free porphyrin derivatives demonstrated high third-order nonlinear optical susceptibility values of 10−10 esu. • Meso-tetrakis (2-thienyl) porphyrin reached the two-photon absorption cross section of 4076 GM. • The mechanisms of third-order nonlinearity were proposed by the pump-probe experiment. [ABSTRACT FROM AUTHOR]